The power transmitting apparatus, to transmit the engine power of vehicle to its wheels, transmits power from an engine to the wheels. The power transmitting apparatus enables radial and axial displacement of the wheels and moment variation. Accordingly, a drive shaft interposed between the engine and the driving wheel is connected at its one end to a differential gear, via a constant velocity universal joint of the slide type, and at the other end to the driving wheel, via a bearing apparatus for the driving wheel which includes an immovable constant velocity universal joint.
Several types of bearing apparatus for a wheel of a vehicle have been proposed, and for example one is shown in FIG. 5. The bearing apparatus for a wheel of a vehicle 50 includes a wheel hub 51, able to mount on its one end a driving wheel W and a brake rotor B, a double row rolling bearing 52, and an immovable constant velocity universal joint 53. The joint 53 is connected to the wheel hub 51 to transmit power of the drive shaft (not shown) to the wheel hub 51.
The wheel hub 51 has an integrally formed wheel mounting flange 54 at one end to mount the driving wheel W and brake rotor B. The wheel hub 51 also has an axially extending cylindrical portion 51a of a smaller diameter. The double row rolling bearing 52, formed as a double row angular ball bearing, has an outer ring 55, a pair of inner rings 56, and a double row of balls 58 held by cage 57. The outer ring 55, on its inner circumferential surface, is formed with double row outer raceway surfaces 55a. The rolling bearing 52 is arranged between a knuckle N, forming a part of a suspension apparatus, and the cylindrical portion 51a of the wheel hub 51. The pair of inner rings 56 are each formed with an inner raceway surface 56a arranged opposite to the double row outer raceway surfaces 55a. The double row balls 58 are freely rollably contained in the cage 57 between the outer and inner raceway surfaces 55a and 56a. 
The constant velocity universal joint 53 has a cup-shaped mouth portion (not shown), a shoulder portion 59 and an outer joint member 61. The shoulder portion 59 forms a bottom portion of the mouth portion. The outer joint member 61 is integrally formed with a shaft portion 60 which axially extends from the shoulder portion 59. The outer joint member 61 is adapted to be inserted into the wheel hub 51, via serrations, in a torque transmitting manner. The shaft portion 60 is inserted into the wheel hub 51 until the shoulder portion 59 abuts the inner ring 56 of the double row rolling bearing 52. The constant velocity universal joint 53 is fastened at a predetermined fastening torque by a securing nut 63 secured onto a male thread 62 formed on the shaft portion 60. Thus, the wheel hub 51 and the outer joint member 61 can be axially separably connected to each other.
The driving wheel W is driven by an engine with a large torque, via a slide type constant velocity universal joint (not shown), at a low engine speed, for example at start-up of the vehicle. Thus, torsional deformation is caused in the drive shaft. This torsional deformation also causes torsional deformation in the inner ring 56 of the double row rolling bearing 52 supporting the drive shaft. When a large tortional deformation is caused in the drive shaft, if there is a circumferential gap between the serrations of the shaft portion 60 of the outer joint member 61 inserted into the wheel hub 51, a so-called “stick slip noise” is caused by abrupt slipping between the contacting surfaces of the outer joint member 61 and the inner ring 56.
One way to prevent the generation of the stick slip noise is to surface machine treat the end surface of the inner ring 56 which abuts the shoulder portion 59 of the outer joint member 61. That is, as shown in FIGS. 6 (a) and (b), grease grooves 64 are formed on the end faces 56b and 56c of the inner rings 56 to hold and promote lubricant, such as grease, in the grease grooves 64 in order to reduce frictional resistance between the abutting surfaces. Thus, this reduces or prevents the generation of the stick slip noise (see Japanese Laid-open Patent Publication No. 110840/2000).
However the lubricant, such as grease, after being applied to the abutting surfaces (end surfaces of the inner ring 56) is often placed in contact with a surface of a work table during assembly. Thus, this contact soils the lubricant during the assembling processes especially when the bearing apparatus is laid on the working table with its end, inner ring side, down in order to stabilize the joint in an upstanding condition on the table. In addition, the quality of the assembled products would be spoiled by foreign matter which enters the grease from the working table